Cast aluminum alloys comprising calcium and related processes

ABSTRACT

Described are processes for continuously casting aluminum alloys, wherein the alloys comprise or are modified to comprise Mg. The processes involve adding Ca to the molten aluminum alloy prior to casting in order to decrease surface defects and exudates in the cast aluminum alloys.

PRIORITY

This application claims priority to U.S. Provisional Application No. 63/199,806, filed Jan. 26, 2021, the entire contents and disclosure of which are incorporated herein.

FIELD

The present disclosure relates to the fields of metallurgy, aluminum alloys, aluminum fabrication, and related fields. In particular, the present disclosure provides cast aluminum alloy compositions which include calcium, and processes for forming the cast aluminum alloys and aluminum alloy articles.

BACKGROUND

Aluminum (Al) alloys are increasingly replacing steel and other metals in multiple applications, such as automotive, transportation, industrial, or electronics-related applications. In some applications, such alloys may need to exhibit high strength, high formability, corrosion resistance, and/or low weight. However, producing alloys having the aforementioned properties is a challenge, as conventional methods and compositions may not achieve the necessary requirements, specifications, and/or performances required for the different applications when produced via established methods. For example, aluminum alloys with a high solute content, including copper (Cu), magnesium (Mg), and zinc (Zn), can exhibit cracking when cast, as well as other surface imperfections.

One known method for addressing such surface imperfections is to scalp the surface of the ingot, which involves machining off a surface layer of the ingot. Another known method for addressing surface imperfections is to include beryllium in the alloy. Although beryllium was effective at controlling surface defects in aluminum cast ingots, it is no longer allowed in food or beverage packaging and is a health concern for factory workers.

SUMMARY

Covered embodiments of the present disclosure are defined by the claims, not this summary. This summary is a high-level overview of various aspects of the invention and introduces some of the concepts that are further described in the Detailed Description section below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification, any or all drawings and each claim.

Provided herein are aluminum alloys that exhibit high strength and high formability, and that do not exhibit cracking and have reduced surface defects during and/or after casting, along with methods of making and processing the alloys. The alloys can be used in automotive, transportation, aerospace, industrial, and electronics applications, to name a few.

In some examples, a process of producing an aluminum alloy product comprises continuously casting an aluminum alloy to form a slab, wherein the aluminum alloy comprises at least 2.0% by weight Mg and, in molten form, the alloy comprises from 30 ppm to 500 ppm calcium (Ca). In some cases, the cast slab does not exhibit cracking during and/or after casting. In some cases, the slab has reduced surface defects as compared to a slab without the calcium addition.

Also provided herein are aluminum alloy articles prepared according to the methods described herein. The aluminum alloy product can be an aluminum alloy sheet, an aluminum alloy plate, or an aluminum alloy shate, having an improved surface. The surface may be viewed visually, through microscopy, to view the size and amount of exudates, as well as the shine of the surface. The aluminum alloy articles prepared according to the methods herein have a more uniform surface with less open porosity than aluminum alloy articles prepared without calcium addition. Additionally, the intermetallic particles are small and well distributed. Depending on the aluminum alloy, such as for 7xxx allowy, the aluminum alloy product can comprise a long traverse tensile yield strength of at least 560 MPa when in a T6 temper. Optionally, the aluminum alloy product can comprise a bend angle of from approximately 80° to approximately 120° when in a T6 temper, such as in alloys other than 5xxx alloys. Optionally, the aluminum alloy product can comprise a yield strength of from approximately 500 MPa to approximately 650 MPa when in a T4 temper and after paint baking. The aluminum alloy product can optionally be an automotive body part, a motor vehicle part, a transportation body part, an aerospace body part, or an electronics housing.

Other objects and advantages of the invention will be apparent from the following detailed description of embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a digital image showing the surface of an aluminum alloy according to an example described herein.

FIG. 2 . is a digital image showing the surface of an aluminum alloy according to an example described herein.

FIG. 3 is a digital image showing the surface of aluminum alloys according to an example described herein.

FIG. 4 is a micrograph image showing the surface of aluminum alloys according to an example described herein.

FIG. 5 is a digital image showing the surface of an aluminum alloy during processing according to an example described herein.

FIG. 6 is a digital image showing the surface of an aluminum alloy during processing according to an example described herein.

FIG. 7 is a digital image showing the surface of an aluminum alloy during processing according to an example described herein.

FIG. 8 is a digital image showing the surface of an aluminum alloy during processing according to an example described herein.

FIG. 9 is a digital image showing the surface of aluminum alloys according to an example described herein.

FIG. 10 is a micrograph image showing the surface of an aluminum alloy according to an example described herein.

FIG. 11 is a micrograph image showing the surface of an aluminum alloy according to an example described herein.

FIG. 12 is a composite micrograph image showing the cross-section of an aluminum alloy according to an example described herein.

FIG. 13 is a micrograph image showing the surface of an aluminum alloy according to an example described herein.

FIG. 14 is a micrograph image showing the surface of an aluminum alloy according to an example described herein.

FIG. 15 is a composite micrograph image showing the cross-section of an aluminum alloy according to an example described herein.

FIG. 16 is a micrograph image showing the surface of an aluminum alloy according to an example described herein.

FIG. 17 is a micrograph image showing the surface of an aluminum alloy according to an example described herein.

FIG. 18 is a composite micrograph image showing the cross-section of an aluminum alloy according to an example described herein.

FIG. 19 is an XRD of extracted particles of an aluminum alloy according to an example described herein.

DETAILED DESCRIPTION

Described herein are aluminum alloys comprising magnesium, wherein when the aluminum alloy is in molten form, calcium is added to the alloy prior to continuous casting. In some cases, aluminum alloys comprising magnesium can be difficult to cast using conventional casting processes due to their magnesium content. The disclosed processes can permit the casting of aluminum alloys comprising magnesium described herein in thin gauges (e.g., aluminum alloy bodies with a thickness of from approximately 5 mm to approximately 50 mm), free from cracking during and/or after casting as determined by visual inspection (e.g., there are fewer cracks per square meter in the slab prepared according to methods described herein than in a direct chill cast ingot). Additionally, the alloys have less surface defects than those formed by processes without calcium addition. In some examples, the aluminum alloys can be continuously cast according to processes as described herein.

Definitions and Descriptions

As used herein, the terms “invention,” “the invention,” “this invention” and “the present invention” are intended to refer broadly to all of the subject matter of this patent application and the claims below. Statements containing these terms should be understood not to limit the subject matter described herein or to limit the meaning or scope of the patent claims below.

As used herein, the meaning of “metals” includes pure metals, alloys and metal solid solutions unless the context clearly dictates otherwise.

In this description, reference is made to alloys identified by aluminum industry designations, such as “series” or “5xxx.” For an understanding of the number designation system most commonly used in naming and identifying aluminum and its alloys, see “International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys,” or “Registration Record of Aluminum Association Alloy Designations and Chemical Compositions Limits for Aluminum Alloys in the Form of Castings and Ingot,” both published by The Aluminum Association.

As used herein, the meaning of “a,” “an,” or “the” includes singular and plural references unless the context clearly dictates otherwise.

As used herein, a plate generally has a thickness of greater than approximately 15 mm. For example, a plate may refer to an aluminum product having a thickness of greater than approximately 15 mm, greater than approximately 20 mm, greater than approximately 25 mm, greater than approximately 30 mm, greater than approximately 35 mm, greater than approximately mm, greater than approximately 45 mm, greater than approximately 50 mm, or greater than approximately 100 mm.

As used herein, a shate (also referred to as a sheet plate) generally has a thickness of from approximately 4 mm to approximately 15 mm. For example, a shate may have a thickness of approximately 4 mm, approximately 5 mm, approximately 6 mm, approximately 7 mm, approximately 8 mm, approximately 9 mm, approximately 10 mm, approximately 11 mm, approximately 12 mm, approximately 13 mm, approximately 14 mm, or approximately 15 mm.

As used herein, a sheet generally refers to an aluminum product having a thickness of less than approximately 4 mm (e.g., less than 3 mm, less than 2 mm, less than 1 mm, less than 0.5 mm, less than 0.3 mm, or less than 0.1 mm). For example, a sheet may have a thickness of approximately 0.1 mm, approximately 0.2 mm, approximately 0.3 mm, approximately 0.4 mm, approximately 0.5, approximately 0.6 mm, approximately 0.7 mm, approximately 0.8 mm, approximately 0.9 mm, approximately 1 mm, approximately 1.1 mm, approximately 1.2 mm, approximately 1.3 mm, approximately 1.4 mm, approximately 1.5 mm, approximately 1.6 mm, approximately 1.7 mm, approximately 1.8 mm, approximately 1.9 mm, approximately 2 mm, approximately 2.1 mm, approximately 2.2 mm, approximately 2.3 mm, approximately 2.4 mm, approximately 2.5 mm, approximately 2.6 mm, approximately 2.7 mm, approximately 2.8 mm, approximately 2.9 mm, approximately 3 mm, approximately 3.1 mm, approximately 3.2 mm, approximately 3.3 mm, approximately 3.4 mm, approximately 3.5 mm, approximately 3.6 mm, approximately 3.7 mm, approximately 3.8 mm, or approximately 3.9 mm.

As used herein, formability refers to the ability of a material to undergo deformation into a desired shape without fracturing, tearing-off, necking, earing, or shaping errors such as wrinkling, spring-back, or galling occurring. In some cases, formability may be classified according to deformation modes. Examples of deformation modes include drawing, stretching, bending, and stretch-flanging.

Reference may be made in this application to alloy temper or condition. For an understanding of the alloy temper descriptions most commonly used, see “American National Standards (ANSI) H35 on Alloy and Temper Designation Systems.” An F condition or temper refers to an aluminum alloy as fabricated. An O condition or temper refers to an aluminum alloy after annealing. An Hxx condition or temper, also referred to herein as an H temper, refers to a non-heat treatable aluminum alloy after cold rolling with or without thermal treatment (e.g., annealing). Suitable H tempers include HX1, HX2, HX3 HX4, HX5, HX6, HX7, HX8, or HX9 tempers. A T1 condition or temper refers to an aluminum alloy cooled from hot working and naturally aged (e.g., at room temperature). A T2 condition or temper refers to an aluminum alloy cooled from hot working, cold worked and naturally aged. A T3 condition or temper refers to an aluminum alloy solution heat treated, cold worked, and naturally aged. A T4 condition or temper refers to an aluminum alloy solution heat treated and naturally aged. A T5 condition or temper refers to an aluminum alloy cooled from hot working and artificially aged (at elevated temperatures). A T6 condition or temper refers to an aluminum alloy solution heat treated and artificially aged. A T7 condition or temper refers to an aluminum alloy solution heat treated and artificially overaged. A T8 condition or temper refers to an aluminum alloy solution heat treated, cold worked, and artificially aged. A T9 condition or temper refers to an aluminum alloy solution heat treated, artificially aged, and cold worked. A W condition or temper refers to an aluminum alloy after solution heat treatment.

As used herein, the “forming temper” refers to a temper in which the aluminum alloy can be deformed to a greater extent than a high strength temper. For example, a 6xxx series aluminum alloy can be deformed to a greater extent in a T4 temper than a T6 temper; thus, the T4 temper can be referred to as a forming temper in this example.

As used herein, the “high strength temper” refers to a temper in which the aluminum alloy is artificially aged to peak age strength. For example, a 6xxx series aluminum alloy can be solution heat treated and artificially aged to a T6 temper to obtain a peak age strength. Additionally, exemplary high strength tempers can include T6, T7, T8, or T9 tempers.

As used herein, the meaning of “room temperature” can include a temperature of from about 15° C. to about 30° C., for example about 15° C., about 16° C., about 17° C., about 18° C., about 19° C., about 20° C., about 21° C., about 22° C., about 23° C., about 24° C., about 25° C., about 26° C., about 27° C., about 28° C., about 29° C., or about 30° C.

All ranges disclosed herein are to be understood to encompass both endpoints and any and all subranges subsumed therein. For example, a stated range of “1 to 10” should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more, e.g. 1 to 6.1, and ending with a maximum value of 10 or less, e.g., 5.5 to 10. All values modified by “approximately” include the exact value as well.

Aluminum Alloys and Articles

Aluminum alloy properties are partially determined by the composition of the aluminum alloys. In certain aspects, the alloy composition may influence or even determine whether the alloy will have properties adequate for a desired forming application.

The aluminum alloy articles described herein can be made of any suitable aluminum alloy, so long as the alloy contains Mg or is modified to contain Mg, including 5xxx series aluminum alloys or 7xxx series aluminum alloys.

Suitable 5xxx series aluminum alloys include, for example, AA5017, AA5018, AA5018A, AA5018B, AA5019, AA5019A, AA5119, AA5119A, AA5021, AA5022, AA5023, AA5024, AA5026, AA5027, AA5028, AA5041, AA5052, AA5049, AA5149, AA5249, AA5349, AA5449, AA5449A, AA5051, AA5051A, AA5151, AA5251, AA5251A, AA5351, AA5451, AA5052, AA5252, AA5352, AA5154, AA5154A, AA5154B, AA5154C, AA5254, AA5354, AA5454, AA5554, AA5454, AA5454A, AA5754, AA5854, AA5954, AA5056, AA5356, AA5356A, AA5456, AA5456A, AA5456B, AA5556, AA5556A, AA5556B, AA5556C, AA5058, AA5059, AA5070, AA5180, AA5180A, AA5082, AA5182, AA5083, AA5183, AA5183A, AA5283, AA5283A, AA5283B, AA5383, AA5483, AA5086, AA6186, AA6087, AA5187, and AA5088.

Suitable 7xxx series aluminum alloys include, for example, AA7004, AA7204, AA7009, AA7010, AA7012, AA7014, AA7015, AA7017, AA7019, AA7019A, AA7022, AA7122, AA7023, AA7028, AA7029, AA7129, AA7229, AA7032, AA7033, AA7034, AA7035, AA7035A, AA7036, AA7136, AA7037, AA7039, AA7040, AA7140, AA7041, AA7042, AA7049, AA7049A, AA7349, AA7449, AA7050, AA7050A, AA7150, AA7055, AA7155, AA7255, AA7056, AA7060, AA7160, AA7064, AA7068, AA7168, AA7075, AA7175, AA7475, AA7076, AA7178, AA7278, AA7278A, AA7081, AA7181, AA7090, AA7093, AA7095, AA7097, AA7099, and AA7199.

In addition to the above alloy which comprise Mg in an amount of approximately 2% by weight or greater, any alloy may be used so long as Mg is added to the alloy, e.g., by adding Mg to the alloy when the alloy is in molten form.

In some cases, the aluminum alloy includes a non-heat treatable alloy. For example, the alloy can include a 1xxx series aluminum alloy, a 3xxx series aluminum alloy, a 4xxx series aluminum alloy, or a 5xxx series aluminum alloy other than those described above. The 1xxx, 3xxx, 4xxx, or 5xxx series aluminum alloys can be modified to include an amount of Mg as described above.

Suitable 1xxx series aluminum alloys include, for example, AA1050, AA1060, AA1070, AA1100, AA1100A, AA1200, AA1200A, AA1300, AA1110, AA1120, AA1230, AA1230A, AA1235, AA1435, AA1145, AA1345, AA1445, AA1150, AA1350, AA1350A, AA1450, AA1370, AA1275, AA1185, AA1285, AA1385, AA1188, AA1190, AA1290, AA1193, AA1198, and AA1199.

Suitable 3xxx series aluminum alloys include, for example, AA3002, AA3102, AA3003, AA3103, AA3103A, AA3103B, AA3203, AA3403, AA3004, AA3004A, AA3104, AA3204, AA3304, AA3005, AA3005A, AA3105, AA3105A, AA3105B, AA3007, AA3107, AA3207, AA3207A, AA3307, AA3009, AA3010, AA3110, AA3011, AA3012, AA3012A, AA3013, AA3014, AA3015, AA3016, AA3017, AA3019, AA3020, AA3021, AA3025, AA3026, AA3030, AA3130, and AA3065.

Suitable 4xxx series aluminum alloys include, for example, AA4004, AA4104, AA4006, AA4007, AA4008, AA4009, AA4010, AA4013, AA4014, AA4015, AA4015A, AA4115, AA4016, AA4017, AA4018, AA4019, AA4020, AA4021, AA4026, AA4032, AA4043, AA4043A, AA4143, AA4343, AA4643, AA4943, AA4044, AA4045, AA4145, AA4145A, AA4046, AA4047, AA4047A, and AA4147.

In some cases, the aluminum alloy includes a heat treatable alloy. For example, the alloy can include a 6xxx series aluminum alloy or a 7xxx series aluminum alloy other than those described above. The 6xxx, or 7xxx series aluminum alloys can be modified to include an amount of Mg as described above.

Suitable 6xxx series aluminum alloys include, for example, AA6101, AA6101A, AA6101B, AA6201, AA6201A, AA6401, AA6501, AA6002, AA6003, AA6103, AA6005, AA6005A, AA6005B, AA6005C, AA6105, AA6205, AA6305, AA6006, AA6106, AA6206, AA6306, AA6008, AA6009, AA6010, AA6110, AA6110A, AA6011, AA6111, AA6012, AA6012A, AA6013, AA6113, AA6014, AA6015, AA6016, AA6016A, AA6116, AA6018, AA6019, AA6020, AA6021, AA6022, AA6023, AA6024, AA6025, AA6026, AA6027, AA6028, AA6031, AA6032, AA6033, AA6040, AA6041, AA6042, AA6043, AA6151, AA6351, AA6351A, AA6451, AA6951, AA6053, AA6055, AA6056, AA6156, AA6060, AA6160, AA6260, AA6360, AA6460, AA6460B, AA6560, AA6660, AA6061, AA6061A, AA6261, AA6361, AA6162, AA6262, AA6262A, AA6063, AA6063A, AA6463, AA6463A, AA6763, A6963, AA6064, AA6064A, AA6065, AA6066, AA6068, AA6069, AA6070, AA6081, AA6181, AA6181A, AA6082, AA6082A, AA6182, AA6091, and AA6092.

In some cases, the properties of the alloys can be achieved at least in part due to the elemental composition of the alloys. In some embodiments, the aluminum alloys can be heat treatable, age hardenable alloys. Optionally, the aluminum alloys can be aluminum alloys classified as 5xxx series aluminum alloys (e.g., wherein Mg is the predominant alloying element) or 7xxx series aluminum alloys (e.g., wherein zinc is a predominant alloying element). In some cases, the aluminum alloys can be modified 1xxx series, 2xxx series, 3xxx series, 4xxx series, 5xxx series, 6xxx series, or 7xxx series aluminum alloys. In some specific aspects, the aluminum alloy is a 5xxx series aluminum alloy or a 7xxx series aluminum alloy comprising at least 2% by weight Mg. As used herein, the term “modified” as related to a series of aluminum alloys refers to an alloy composition that would typically be classified within a particular series, but the modification of one or more elements (types or amounts) results in a different predominant alloying element, e.g., magnesium.

In some embodiments, the composition of an aluminum alloy may affect its response to the continuous casting processes. For example, the strength during or after continuous casting may be affected by an amount of Mg present in the alloy.

Aluminum alloy articles, formed by the calcium addition process described herein, surprisingly and unexpectedly had less exudates, smaller exudates, or both, than articles formed without such calcium addition. Additionally, the alloys had a more uniform surface with less open porosity that is associated with exudates. The intermetallic particles were also small and well dispersed. In some aspects, the articles formed by the processes described herein resulted in at least a 10% reduction in the number of exudates, e.g., at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, or at least 70%, when compared to articles formed by the same process except for the Ca addition. Similarly, in some aspects, the articles formed by the processes described herein resulted in at least a 10% reduction in the size of exudates, e.g., at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, or at least 70%, when compared to articles formed by the same process except for the Ca addition.

Exemplary Aluminum Alloys

In some embodiments, the aluminum alloy articles described herein can be made from 1xxx series, 2xxx series, 3xxx series, 4xxx series, 5xxx series, 6xxx series, or 7xxx series aluminum alloys. In certain aspects, the alloys exhibit high strength, high formability, and corrosion resistance.

In some aspects, the aluminum alloy (as modified) includes Mg in an amount from approximately 0.3% to approximately 10%, from approximately 0.5% to approximately 10%, from approximately 0.7% to 10%, from approximately 1.0% to approximately 10%, from approximately 2.0% to approximately 10% (e.g., from 2.25% to 10%, from 2.5% to 10%, from 2.5% to 9%, from 2.5% to 8%, from 2.5% to 7.5%, or from 2.5% to 7%) based on the total weight of the alloy. For example, the alloy can include approximately 0.3%, approximately 0.4%, approximately 0.5%, approximately 0.6%, approximately 0.7%, approximately 0.8%, approximately 0.9%, approximately 1.0%, approximately 1.1%, approximately 1.2%, approximately 1.3%, approximately 1.4%, approximately 1.5%, approximately 1.6%, approximately 1.7%, approximately 1.8%, approximately 1.9%, approximately 2%, approximately 2.1%, approximately 2.2%, approximately 2.3%, approximately 2.4%, approximately 2.5%, approximately 2.6%, approximately 2.7%, approximately 2.8%, approximately 2.9%, approximately 3%, approximately 3.1%, approximately 3.2%, approximately 3.3%, approximately 3.4%, approximately 3.5%, approximately 3.6%, approximately 3.7%, approximately 3.8%, approximately 3.9%, approximately 4%, approximately 4.1%, approximately 4.2%, approximately 4.3%, approximately 4.4%, approximately 4.5%, approximately 4.6%, approximately 4.7%, approximately 4.8%, approximately 4.9%, approximately 5%, approximately 5.1%, approximately 5.2%, approximately 5.3%, approximately 5.4%, approximately 5.5%, approximately 5.6%, approximately 5.7%, approximately 5.8%, approximately 5.9%, approximately 6%, approximately 6.1%, approximately 6.2%, approximately 6.3%, approximately 6.4%, approximately 6.5%, approximately 6.6%, approximately 6.7%, approximately 6.8%, approximately 6.9%, approximately 7%, approximately 7.1%, approximately 7.2%, approximately 7.3%, approximately 7.4%, approximately 7.5%, approximately 7.6%, approximately 7.7%, approximately 7.8%, approximately 7.9%, approximately 8%, approximately 8.1%, approximately 8.2%, approximately 8.3%, approximately 8.4%, approximately 8.5%, approximately 8.6%, approximately 8.7%, approximately 8.8%, approximately 8.9%, approximately 9%, approximately 9.1%, approximately 9.2%, approximately 9.3%, approximately 9.4%, approximately 9.5%, approximately 9.6%, approximately 9.7%, approximately 9.8%, approximately 9.9%, or approximately 10% Mg. All expressed in wt. %.

In some aspects, the aluminum alloy includes manganese (Mn) in an amount from 0% to approximately 2% (e.g., from 0.01% to 2%, from 0.05% to 1.75%, from 0.1% to 1.5%, or from % to 1%) based on the total weight of the alloy. For example, the alloy can include 0%, approximately 0.05%, approximately 0.1%, approximately 0.15%, approximately 0.2%, approximately 0.25%, approximately 0.3%, approximately 0.35%, approximately 0.4%, approximately 0.45%, approximately 0.5%, approximately 0.55%, approximately 0.6%, approximately 0.65%, approximately 0.7%, approximately 0.75%, approximately 0.8%, approximately 0.85%, approximately 0.9%, approximately 0.95%, approximately 1%, approximately 1.05%, approximately 1.1%, approximately 1.15%, approximately 1.2%, approximately 1.25%, approximately 1.3%, approximately 1.35%, approximately 1.4%, approximately 1.45%, approximately 1.5%, approximately 1.55%, approximately 1.6%, approximately 1.65%, approximately 1.7%, approximately 1.75%, approximately 1.8%, approximately 1.85%, approximately 1.9%, approximately 1.95%, or approximately 2% Mn. In certain aspects, Mn is not present in the alloy (i.e., 0%). All expressed in wt. %.

In some aspects, the aluminum alloy includes chromium (Cr) in an amount from 0% to approximately 2% (e.g., from 0.01% to 2%, from 0.05% to 1.75%, from 0.1% to 1.5%, or from 0.15% to 1%) based on the total weight of the alloy. For example, the alloy can include 0%, approximately 0.05%, approximately 0.1%, approximately 0.15%, approximately 0.2%, approximately 0.25%, approximately 0.3%, approximately 0.35%, approximately 0.4%, approximately 0.45%, approximately 0.5%, approximately 0.55%, approximately 0.6%, approximately 0.65%, approximately 0.7%, approximately 0.75%, approximately 0.8%, approximately 0.85%, approximately 0.9%, approximately 0.95%, approximately 1%, approximately 1.05%, approximately 1.1%, approximately 1.15%, approximately 1.2%, approximately 1.25%, approximately 1.3%, approximately 1.35%, approximately 1.4%, approximately 1.45%, approximately 1.5%, approximately 1.55%, approximately 1.6%, approximately 1.65%, approximately 1.7%, approximately 1.75%, approximately 1.8%, approximately 1.85%, approximately 1.9%, approximately 1.95%, or approximately 2% Cr. In certain aspects, Cr is not present in the alloy (i.e., 0%). All expressed in wt. %.

In some aspects, the aluminum alloy includes copper (Cu) in an amount from 0% to approximately 2.5% (e.g., from 0.01% to 2.25%, from 0.02% to 2%, from 0.03% to 1.5%, or from 0.04% to 1%) based on the total weight of the alloy. For example, the alloy can include 0%, approximately 0.01%, approximately 0.02%, approximately 0.03%, approximately 0.04%, approximately 0.05%, approximately 0.06%, approximately 0.07%, approximately 0.08%, approximately 0.09%, approximately 0.1%, approximately 0.15%, approximately 0.2%, approximately 0.25%, approximately 0.3%, approximately 0.35%, approximately 0.4%, approximately 0.45%, approximately 0.5%, approximately 0.55%, approximately 0.6%, approximately 0.65%, approximately 0.70%, approximately 0.75%, approximately 0.8%, approximately 0.85%, approximately 0.9%, approximately 0.95%, approximately 1%, approximately 1.05%, approximately 1.1%, approximately 1.15%, approximately 1.2%, approximately 1.25%, approximately 1.3%, approximately 1.35%, approximately 1.4%, approximately 1.45%, approximately 1.5%, approximately 1.55%, approximately 1.6%, approximately 1.65%, approximately 1.7%, approximately 1.75%, approximately 1.8%, approximately 1.85%, approximately 1.9%, approximately 1.95%, approximately 2%, approximately 2.05%, approximately 2.1, approximately 2.15%, approximately 2.2%, approximately 2.25%, approximately 2.3%, approximately 2.35%, approximately 2.4%, approximately 2.45%, or approximately 2.5% Cu. In certain aspects, Cu is not present in the alloy (i.e., 0%). All expressed in wt. %.

In some aspects, the aluminum alloy includes silicon (Si) in an amount from 0% to approximately 2% (e.g., from 0.01% to 2%, from 0.05% to 1.75%, from 0.1% to 1.5%, or from % to 1%) based on the total weight of the alloy. For example, the alloy can include 0%, approximately 0.05%, approximately 0.1%, approximately 0.15%, approximately 0.2%, approximately 0.25%, approximately 0.3%, approximately 0.35%, approximately 0.4%, approximately 0.45%, approximately 0.5%, approximately 0.55%, approximately 0.6%, approximately 0.65%, approximately 0.7%, approximately 0.75%, approximately 0.8%, approximately 0.85%, approximately 0.9%, approximately 0.95%, approximately 1%, approximately 1.05%, approximately 1.1%, approximately 1.15%, approximately 1.2%, approximately 1.25%, approximately 1.3%, approximately 1.35%, approximately 1.4%, approximately 1.45%, approximately 1.5%, approximately 1.55%, approximately 1.6%, approximately 1.65%, approximately 1.7%, approximately 1.75%, approximately 1.8%, approximately 1.85%, approximately 1.9%, approximately 1.95%, or approximately 2% Si. In certain aspects, Si is not present in the alloy (i.e., 0%). All expressed in wt. %.

In some aspects, the aluminum alloy includes iron (Fe) in an amount from 0% to approximately 2% (e.g., from 0.01% to 2%, from 0.05% to 1.75%, from 0.1% to 1.5%, or from % to 1%) based on the total weight of the alloy. For example, the alloy can include 0%, approximately 0.05%, approximately 0.1%, approximately 0.15%, approximately 0.2%, approximately 0.25%, approximately 0.3%, approximately 0.35%, approximately 0.4%, approximately 0.45%, approximately 0.5%, approximately 0.55%, approximately 0.6%, approximately 0.65%, approximately 0.7%, approximately 0.75%, approximately 0.8%, approximately 0.85%, approximately 0.9%, approximately 0.95%, approximately 1%, approximately 1.05%, approximately 1.1%, approximately 1.15%, approximately 1.2%, approximately 1.25%, approximately 1.3%, approximately 1.35%, approximately 1.4%, approximately 1.45%, approximately 1.5%, approximately 1.55%, approximately 1.6%, approximately 1.65%, approximately 1.7%, approximately 1.75%, approximately 1.8%, approximately 1.85%, approximately 1.9%, approximately 1.95%, or approximately 2% Fe. In certain aspects, Fe is not present in the alloy (i.e., 0%). All expressed in wt. %.

In some aspects, the aluminum alloy includes zinc (Zn) in an amount from 0% to approximately 10% (e.g., from 0.01% to 10%, from 0.05% to 9%, from 0.1% to 9%, or from 0.15% to 9%) based on the total weight of the alloy. For example, the alloy can include 0%, approximately 0.01%, approximately 0.02%, approximately 0.03%, approximately 0.04%, approximately 0.05%, approximately 0.06%, approximately 0.07%, approximately 0.08%, approximately 0.09%, approximately 0.1%, approximately 0.15%, approximately 0.2%, approximately 0.25%, approximately 0.3%, approximately 0.35%, approximately 0.4%, approximately 0.45%, approximately 0.5%, approximately 0.55%, approximately 0.6%, approximately 0.65%, approximately 0.70%, approximately 0.75%, approximately 0.8%, approximately 0.85%, approximately 0.9%, approximately 0.95%, approximately 1%, approximately 1.1%, approximately 1.2%, approximately 1.3%, approximately 1.4%, approximately 1.5%, approximately 1.6%, approximately 1.7%, approximately 1.8%, approximately 1.9%, approximately 2%, approximately 2.1%, approximately 2.2%, approximately 2.3%, approximately 2.4%, approximately 2.5%, approximately 2.6%, approximately 2.7%, approximately 2.8%, approximately 2.9%, approximately 3%, approximately 3.1%, approximately 3.2%, approximately 3.3%, approximately 3.4%, approximately 3.5%, approximately 3.6%, approximately 3.7%, approximately 3.8%, approximately 3.9%, approximately 4%, approximately 4.1%, approximately 4.2%, approximately 4.3%, approximately 4.4%, approximately 4.5%, approximately 4.6%, approximately 4.7%, approximately 4.8%, approximately 4.9%, approximately 5%, approximately 5.1%, approximately 5.2%, approximately 5.3%, approximately 5.4%, approximately 5.5%, approximately 5.6%, approximately 5.7%, approximately 5.8%, approximately 5.9%, approximately 6%, approximately 6.1%, approximately 6.2%, approximately 6.3%, approximately 6.4%, approximately 6.5%, approximately 6.6%, approximately 6.7%, approximately 6.8%, approximately 6.9%, approximately 7%, approximately 7.1%, approximately 7.2%, approximately 7.3%, approximately 7.4%, approximately 7.5%, approximately 7.6%, approximately 7.7%, approximately 7.8%, approximately 7.9%, approximately 8%, approximately 8.1%, approximately 8.2%, approximately 8.3%, approximately 8.4%, approximately 8.5%, approximately 8.6%, approximately 8.7%, approximately 8.8%, approximately 8.9%, approximately 9%, approximately 9.1%, approximately 9.2%, approximately 9.3%, approximately 9.4%, approximately 9.5%, approximately 9.6%, approximately 9.7%, approximately 9.8%, approximately 9.9%, or approximately 10% Zn. In certain aspects, Zn is not present in the alloy (i.e., 0%). All expressed in wt. %.

In some aspects, the aluminum alloy includes zirconium (Zr) in an amount from 0% to approximately 0.5% (e.g., from 0% to 0.45%, from 0.01% to 0.4%, from 0.01% to 0.35%, from 0.01% to 0.2%, or from 0.02% to 0.1%) based on the total weight of the alloy. For example, the alloy can include 0%, approximately 0.001%, approximately 0.002%, approximately 0.003%, approximately 0.004%, approximately 0.005%, approximately 0.006%, approximately 0.007%, approximately 0.008%, approximately 0.009%, approximately 0.01%, approximately 0.02%, approximately 0.03%, approximately 0.04%, approximately 0.05%, approximately 0.06%, approximately 0.07%, approximately 0.08%, approximately 0.09%, approximately 0.1%, approximately 0.11%, approximately 0.12%, approximately 0.13%, approximately 0.14%, approximately 0.15%, approximately 0.16%, approximately 0.17%, approximately 0.18%, approximately 0.19%, approximately 0.20%, approximately 0.21%, approximately 0.22%, approximately 0.23%, approximately 0.24%, approximately 0.25%, approximately 0.26%, approximately 0.27%, approximately 0.28%, approximately 0.29%, approximately 0.30%, approximately 0.31%, approximately 0.32%, approximately 0.33%, approximately 0.34%, approximately 0.35%, approximately 0.36%, approximately 0.37%, approximately 0.38%, approximately 0.39%, approximately 0.40%, approximately 0.41%, approximately 0.42%, approximately 0.43%, approximately 0.44%, approximately 0.45%, approximately 0.46%, approximately 0.47%, approximately 0.48%, approximately 0.49%, or approximately 0.50% Zr. All expressed in wt. %.

In some aspects, the aluminum alloy includes nickel (Ni) in an amount up to approximately 0.5% (e.g., from 0% to approximately 0.5%, from approximately 0.01% to approximately 0.4%, from approximately 0.01% to approximately 0.35%, from approximately 0.01% to approximately 0.2%, or from approximately 0.02% to approximately 0.1%) based on the total weight of the alloy. For example, the alloy can include approximately 0.001%, approximately 0.002%, approximately 0.003%, approximately 0.004%, approximately 0.005%, approximately 0.006%, approximately 0.007%, approximately 0.008%, approximately 0.009%, approximately 0.01%, approximately 0.02%, approximately 0.03%, approximately 0.04%, approximately 0.05%, approximately 0.06%, approximately 0.07%, approximately 0.08%, approximately 0.09%, approximately 0.1%, approximately 0.11%, approximately 0.12%, approximately 0.13%, approximately 0.14%, approximately 0.15%, approximately 0.16%, approximately 0.17%, approximately 0.18%, approximately 0.19%, approximately 0.20%, approximately 0.21%, approximately 0.22%, approximately 0.23%, approximately 0.24%, approximately 0.25%, approximately 0.26%, approximately 0.27%, approximately 0.28%, approximately 0.29%, approximately 0.30%, approximately 0.31%, approximately 0.32%, approximately 0.33%, approximately 0.34%, approximately 0.35%, approximately 0.36%, approximately 0.37%, approximately 0.38%, approximately 0.39%, approximately 0.40%, approximately 0.41%, approximately 0.42%, approximately 0.43%, approximately 0.44%, approximately 0.45%, approximately 0.46%, approximately 0.47%, approximately 0.48%, approximately 0.49%, or approximately 0.50 Ni. All expressed in wt. %.

In certain aspects, the aluminum alloy includes tin (Sn) in an amount up to approximately 0.25% (e.g., from 0% to approximately 0.25%, from 0% to approximately 0.2%, from 0% to approximately 0.05%, from approximately 0.01% to approximately 0.15%, or from approximately 0.01% to approximately 0.1%) based on the total weight of the alloy. For example, the alloy can include approximately 0.001%, approximately 0.002%, approximately 0.003%, approximately 0.004%, approximately 0.005%, approximately 0.006%, approximately 0.007%, approximately 0.008%, approximately 0.009%, approximately 0.01%, approximately 0.02%, approximately 0.03%, approximately 0.04%, approximately 0.05%, approximately 0.06%, approximately 0.07%, approximately 0.08%, approximately 0.09%, approximately 0.1%, approximately 0.11%, approximately 0.12%, approximately 0.13%, approximately 0.14%, approximately 0.15%, approximately 0.16%, approximately 0.17%, approximately 0.18%, approximately 0.19%, approximately 0.20%, approximately 0.21%, approximately 0.22%, approximately 0.23%, approximately 0.24%, or approximately 0.25%, Sn. All expressed in wt. %.

In certain aspects, the aluminum alloy includes titanium (Ti) in an amount up to approximately 0.1% (e.g., from 0.01% to 0.1%,) based on the total weight of the alloy. For example, the alloy can include approximately 0.001%, approximately 0.002%, approximately 0.003%, approximately 0.004%, approximately 0.005%, approximately 0.006%, approximately 0.007% approximately 0.008%, approximately 0.009% approximately 0.01%, approximately 0.011%, approximately 0.012%, approximately 0.013%, approximately 0.014%, approximately 0.015%, approximately 0.016% approximately 0.017% approximately 0.018% approximately 0.019%, approximately 0.02%, approximately 0.021%, approximately 0.022%, approximately 0.023%, approximately 0.024%, approximately 0.025%, approximately 0.026%, approximately 0.027%, approximately 0.028%, approximately 0.029%, approximately 0.03%, approximately 0.031%, approximately 0.032%, approximately 0.033%, approximately 0.034%, approximately 0.035% approximately 0.036% approximately 0.037% approximately 0.038% approximately 0.039%, approximately 0.04%, approximately 0.05%, approximately 0.051%, approximately 0.052% approximately 0.053%, approximately 0.054% approximately 0.055%, approximately 0.056%, approximately 0.057%, approximately 0.058%, approximately 0.059%, approximately 0.06%, approximately 0.07%, approximately 0.08%, approximately 0.09%, approximately 0.099%, or approximately 0.1% Ti. All expressed in wt. %.

Optionally, the aluminum alloy compositions can further include other minor elements, sometimes referred to as impurities, in amounts of approximately 0.05% or below, approximately 0.04% or below, approximately 0.03% or below, approximately 0.02% or below, or approximately 0.01% or below each. These impurities may include, but are not limited to, V, Ga, Hf, Sr, or combinations thereof. Accordingly, V, Ga, Hf, or Sr may be present in an alloy in amounts of approximately 0.05% or below, approximately 0.04% or below, approximately 0.03% or below, approximately 0.02% or below, or approximately 0.01% or below. In certain aspects, the sum of all impurities does not exceed approximately 0.15% (e.g., approximately 0.1%). All expressed in wt. %. In certain aspects, the remaining percentage of the alloy is aluminum.

The aluminum alloy may be substantially free of beryllium (Be), e.g., contains approximately 0.01% Be or below, approximately 0.009%, approximately 0.008%, approximately 0.007%, approximately 0.006%, approximately 0.005%, approximately 0.004%, approximately 0.003%, approximately 0.002%, approximately 0.001%, approximately 0.0009%, approximately 0.0008%, approximately 0.0007%, approximately 0.0006%, approximately 0.0005%, approximately 0.0004%, approximately 0.0003%, approximately 0.002%, approximately 0.0001%, or 0% Be.

As described below, once the aluminum alloy is in molten form, calcium (Ca) is added to the molten alloy. In molten form, the aluminum alloy includes Ca in an amount up to approximately 500 ppm (e.g., from 30 ppm to 500 ppm, from 40 ppm to 500 ppm, from 50 ppm to 500 ppm, from 50 ppm to 400 ppm, or from 50 ppm to 250 ppm) based on the total weight of the alloy. For example, the alloy can include approximately 30 ppm, approximately 35 ppm, approximately 40 ppm, approximately 45 ppm, approximately 50 ppm, approximately 55 ppm, approximately 60 ppm, approximately 65 ppm, approximately 70 ppm, approximately 75 ppm, approximately 80 ppm, approximately 85 ppm, approximately 90 ppm, approximately 95 ppm, approximately 100 ppm, approximately 105 ppm, approximately 110 ppm, approximately 115 ppm, approximately 120 ppm, approximately 125 ppm, approximately 130 ppm, approximately 135 ppm, approximately 140 ppm, approximately 145 ppm, approximately 150 ppm, approximately 155 ppm, approximately 160 ppm, approximately 165 ppm, approximately 170 ppm, approximately 175 ppm, approximately 180 ppm, approximately 185 ppm, approximately 190 ppm, approximately 195 ppm, approximately 200 ppm, approximately 205 ppm, approximately 210 ppm, approximately 215 ppm, approximately 220 ppm, approximately 225 ppm, approximately 230 ppm, approximately 235 ppm, approximately 240 ppm, approximately 245 ppm, approximately 250 ppm, approximately 255 ppm, approximately 260 ppm, approximately 265 ppm, approximately 270 ppm, approximately 275 ppm, approximately 280 ppm, approximately 285 ppm, approximately 290 ppm, approximately 295 ppm, approximately 300 ppm, approximately 305 ppm, approximately 310 ppm, approximately 315 ppm, approximately 320 ppm, approximately 325 ppm, approximately 330 ppm, approximately 335 ppm, approximately 340 ppm, approximately 345 ppm, approximately 350 ppm, approximately 355 ppm, approximately 360 ppm, approximately 365 ppm, approximately 370 ppm, approximately 375 ppm, approximately 380 ppm, approximately 385 ppm, approximately 390 ppm, approximately 395 ppm, approximately 400 ppm, approximately 405 ppm, approximately 410 ppm, approximately 415 ppm, approximately 420 ppm, approximately 425 ppm, approximately 430 ppm, approximately 435 ppm, approximately 440 ppm, approximately 445 ppm, approximately 450 ppm, approximately 455 ppm, approximately 460 ppm, approximately 465 ppm, approximately 470 ppm, approximately 475 ppm, approximately 480 ppm, approximately 485 ppm, approximately 490 ppm, approximately 495 ppm, or approximately 500 ppm Ca. All expressed in ppm by weight.

Methods of Making

Methods of producing an aluminum article are also described herein. The aluminum alloy can be cast and then further processing steps may be performed. In some examples, the processing steps include an optional quenching step, a pre-heating and/or a homogenizing step, a hot rolling step, a solutionizing step, an artificial aging step, an optional coating step and an optional paint baking step.

In some examples, the method comprises casting a slab; hot rolling the slab to produce a hot rolled aluminum alloy in a form of a sheet, shate or plate; solutionizing the aluminum sheet, shate or plate; and aging the aluminum sheet, shate or plate. In some examples, the slabs are thermally quenched upon exit from the continuous caster. In some further examples, the slabs are coiled upon exit from the continuous caster. In some cases, the coiled slabs are cooled in air. In some instances, the method further includes preheating the coiled slabs. In some instances, the method further includes coating the aged aluminum sheet, shate, or plate. In some further instances, the method further includes paint baking the coated aluminum sheet, shate, or plate. The method steps are further described below.

Casting

The alloys described herein can be cast into slabs using a continuous casting (CC) process. As described above, the aluminum alloy is melted and when in molten form, Ca is added to the alloy. If necessary, Mg may also be added to the alloy in molten form. In some aspects, the Mg is added within 5 hours of casting to reduce oxidation of the Mg. The Ca may be added to the molten alloy at any point of the process prior to casting, including when feeding the molten alloy to the casting device, i.e., in the trough.

The continuous casting device can be any suitable continuous casting device. The continuous casting process can include, but is not limited to, the use of block casters, twin roll casters or twin belt casters. The continuous casting can be performed at rates up to approximately 35 meters/minute (m/min).

The resulting cast aluminum alloy (slab) can have a thickness of approximately 1 mm to approximately 50 mm (e.g., from approximately 10 mm to approximately 45 mm, from approximately 15 mm to approximately 40 mm, or from approximately 20 mm to approximately 35 mm), such as approximately 10 mm. For example, the resulting slab can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, 25 mm, 26 mm, 27 mm, 28 mm, 29 mm, 30 mm, 31 mm, 32 mm, 33 mm, 34 mm, 35 mm, 36 mm, 37 mm, 38 mm, 39 mm, 40 mm, 41 mm, 42 mm, 43 mm, 44 mm, 45 mm, 46 mm, 47 mm, 48 mm, 49 mm, or 50 mm thick.

Quenching

The resulting slabs can optionally be thermally quenched upon exit from the continuous caster. In some examples, the quench is performed with water. Optionally, the water quenching step can be performed at a rate of up to approximately 200° C./s (for example, from 10° C./s to 190° C./s, from 25° C./s to 175° C./s, from 50° C./s to 150° C./s, from 75° C./s to 125° C./s, or from 10° C./s to 50° C./s). The water temperature can be from approximately 20° C. to approximately 75° C. (e.g., approximately 25° C., approximately 30° C., approximately 35° C., approximately 40° C., approximately 45° C., approximately 50° C., approximately 55° C., approximately 60° C., approximately 65° C., approximately 70° C., or approximately 75° C.). Optionally, the resulting slabs can be coiled upon exit from the continuous caster. The resulting intermediate coil can be cooled in air. The air cooling step can be performed at a rate of approximately 1° C./s to approximately 300° C./day.

In some examples, water quenching the slab upon exit from the continuous caster results in an aluminum alloy slab in a T4-temper condition. After the optional water quenching, the slab in T4-temper can then be optionally coiled into an intermediate coil and stored for a time period of up to 24 hours. The defect count and the formation of exudates (e.g., eruptions of iron rich material) is decreased as compared to continuously cast slabs without the addition of the above described amounts of Ca. In some aspects, the cast aluminum alloy comprises an improved surface, as quantified by number or exudates, exudate size, and/or “streaks” in the article. Without being bound by theory, it is believed that by adding Ca to the molten alloy, during casting an oxide surface layer is formed, which reduces surface defects and exudate growth. The oxide layer thickness may be quantified using Scanning Electron microscopy by comparing the Al—O ratio to standards of known oxide thickness. Direct measurement by Transmission Electron microscopy may also be viable. Without being bound by theory, it is also believed that the Ca addition may also help the slab to self-repair of the oxide, such as during hot rolling.

Coiling

Optionally, the slab can be coiled into an intermediate coil upon exit from the continuous caster. In some examples, the slab is coiled into an intermediate coil upon exit from the continuous caster resulting in F-temper. In some further examples, the coil is cooled in air. In some still further examples, the air cooled coil is stored for a period of time. In some examples, the intermediate coils are maintained at a temperature of approximately 100° C. to approximately 350° C. (for example, approximately 200° C. or approximately 300° C.). In some further examples, the intermediate coils are maintained in cold storage to prevent natural aging resulting in F-temper.

Pre-Heating and/or Homogenizing

When stored, the intermediate coils can be optionally reheated in a pre-heating step. In some examples, the reheating step can include pre-heating the intermediate coils for a hot rolling step. In some further examples, the reheating step can include pre-heating the intermediate coils at a rate of up to approximately 150° C./h (for example, approximately 10° C./h or approximately 50° C./h). The intermediate coils can be heated to a temperature of approximately 350° C. to approximately 580° C. (e.g., approximately 375° C. to approximately 570° C., approximately 400° C. to approximately 550° C., approximately 425° C. to approximately 500° C., or approximately 500° C. to approximately 580° C.). The intermediate coils can soak for approximately 1 minute to approximately 120 minutes, preferably approximately 60 minutes.

Optionally, the intermediate coils after storage and/or pre-heating of the coils or the slab upon exit from the caster can be homogenized. The homogenization step can include heating the slab or intermediate coil to attain a peak metal temperature (PMT) of about, or at least about, 450° C. (e.g., at least 460° C., at least 470° C., at least 480° C., at least 490° C., at least 500° C., at least 510° C., at least 520° C., at least 530° C., at least 540° C., at least 550° C., at least 560° C., at least 570° C., or at least 580° C.). For example, the cast aluminum alloy product can be heated to a temperature of from about 450° C. to about 580° C., from about 460° C. to about 575° C., from about 470° C. to about 570° C., from about 480° C. to about 565° C., from about 490° C. to about 555° C., or from about 500° C. to about 550° C. In some cases, the heating rate to the PMT can be about 100° C./hour or less, 75° C./hour or less, 50° C./hour or less, 40 5° C./hour or less, 30° C./hour or less, 25° C./hour or less, 20° C./hour or less, or 15° C./hour or less. In other cases, the heating rate to the PMT can be from about 10° C./min to about 100° C./min (e.g., from about 10° C./min to about 90° C./min, from about 10° C./min to about 70° C./min, from about 10° C./min to about 60° C./min, from about 20° C./min to about 90° C./min, from about 30° C./min to about 80° C./min, from about 40° C./min to about 70° C./min, or from about 50° C./min to about 60° C./min).

The cast aluminum alloy product is then allowed to soak (i.e., held at the indicated temperature) for a period of time. In some cases, the cast aluminum alloy product is allowed to soak for at least 30 minutes at a peak metal temperature as described above. According to one non-limiting example, the cast aluminum alloy product is allowed to soak for up to about 36 hours (e.g., from about 30 minutes to about 36 hours, inclusively). For example, the cast aluminum alloy product can be soaked at the peak metal temperature for 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, 25 hours, 26 hours, 27 hours, 28 hours, 29 hours, 30 hours, 31 hours, 32 hours, 33 hours, 34 hours, 35 hours, 36 hours, or anywhere in between.

Hot Rolling and Coiling

Following the pre-heating and/or homogenization step, a hot rolling step can be performed. The hot rolling step can include a hot reversing mill operation and/or a hot tandem mill operation. The hot rolling step can be performed at a temperature ranging from about 250° C. to about 550° C. (e.g., from about 300° C. to about 500° C. or from about 350° C. to about 450° C.). In certain cases, the cast aluminum alloy product can be hot rolled to an about 4 mm to about 15 mm thick gauge (e.g., from about 5 mm to about 12 mm thick gauge), which is referred to as a shate. For example, the cast aluminum alloy product can be hot rolled to an about 4 mm thick gauge, about 5 mm thick gauge, about 6 mm thick gauge, about 7 mm thick gauge, about 8 mm thick gauge, about 9 mm thick gauge, about 10 mm thick gauge, about 11 mm thick gauge, about 12 mm thick gauge, about 13 mm thick gauge, about 14 mm thick gauge, or about 15 mm thick gauge. In certain cases, the cast aluminum alloy product can be hot rolled to a gauge greater than 15 mm thick (i.e., a plate). In other cases, the cast aluminum alloy product can be hot rolled to a gauge less than 4 mm (i.e., a sheet).

At the end of the hot rolling step, optionally within the single stand mill or a multi-stand mill, the hot rolled product can be rolled up as a coil. The coiling temperature can be at least 285° C. and may range from about 285° C. to about 450° C. (e.g., from about 285° C. to about 400° C., from about 285° C. to about 350° C., from about 300° C. to about 350° C. or from about 310° C. to about 330° C.).

Cold Rolling

A cold rolling step can optionally be applied to the alloy to form a final gauge product. For example, the cast aluminum alloy product can be cold rolled to a thickness of less than about 4 mm. In some examples, a sheet may have a thickness of less than 4 mm, less than 3 mm, less than 2 mm, less than 1 mm, less than 0.9 mm, less than 0.8 mm, less than 0.7 mm, less than 0.6 mm, less than 0.5 mm, less than 0.4 mm, less than 0.3 mm, less than 0.2 mm, or less than 0.1 mm. The temper of the as-rolled sheets is referred to as F-temper.

Deforming

The process described herein can optionally include at least one deforming step applied to the final gauge product. The term “deforming,” as used herein, includes cutting, stamping, pressing, press-forming, drawing, shaping, straining or other processes that can create two- or three-dimensional shapes as known to one of ordinary skill in the art. The deforming step can be performed on an aluminum alloy sheet, plate, or shate that has a temperature of about room temperature (e.g., from about 15° C. to about 30° C.) (referred to as cold forming) or that has been heated to an elevated temperature (referred to as a warm forming process or a hot forming process). In some examples, a warm forming procedure can be applied to form an aluminum alloy product. In these examples, the warm forming can include heating the aluminum alloy product to a temperature of about 40° C. to less than about 100° C. In other examples, a hot forming procedure can be applied to form an aluminum alloy article. In these examples, the hot forming can include heating the aluminum alloy product to temperatures of about 100° C. to about 600° C. at a heating rate of about 3° C./second to about 90° C./second, deforming the aluminum alloy product to form an aluminum alloy article, optionally repeating the deforming step and cooling the article. In some examples, a cryogenic forming procedure can be applied to form an aluminum alloy product. In these examples, the cryogenic forming can include cooling the aluminum alloy product to a temperature of about 0° C. to about −200° C.

The method of producing the aluminum alloy products described herein can exclude heat treatment steps. In some examples, the method of producing an aluminum product excludes a paint baking step. In some examples, the method of producing an aluminum product excludes an artificial aging step. In some examples, the method of producing an aluminum product excludes an annealing step.

Aging

Optionally, the hot rolled metal is subjected to an artificial aging step. The artificial aging step develops the high strength property of the alloys and optimizes other desirable properties in the alloys. The mechanical properties of the final product can be controlled by various aging conditions depending on the desired use. In some cases, the metal product described herein can be delivered to customers in a Tx temper (a T1 temper, a T4 temper, a T5 temper, a T6 temper, a T7 temper, or a T8 temper, for example), a W temper, an O temper, or an F temper. In some examples, an artificial aging step can be performed. The artificial aging step can be performed at a temperature from approximately 100° C. to approximately 140° C. (e.g., at approximately 120° C. or at approximately 125° C.). The artificial aging step can be performed for a period of time from approximately 12 hours to approximately 36 hours (e.g., for approximately 18 hours or for approximately 24 hours). In some examples, the artificial aging step can be performed at 125° C. for 24 hours to result in a T6 temper. In some still further examples, the alloys are subjected to a natural aging step. The natural aging step can result in a T4 temper.

Coating and/or Paint Baking

Optionally, the metal product is subjected to a coating step. Optionally, the coating step can include zinc phosphating (Zn-phosphating) and electrocoating (E-coating). The Zn-phosphating and E-coating are performed according to standards commonly used in the aluminum industry as known to one of skill in the art. Optionally, the coating step can be followed by a paint baking step. The paint baking step can be performed at a temperature of approximately 150° C. to approximately 230° C. (e.g., at approximately 180° C. or at approximately 210° C.). The paint baking step can be performed for a time period of approximately 10 minutes to approximately 60 minutes (e.g., approximately 30 minutes or approximately 45 minutes).

Properties

The resulting metal product as described herein has a combination of desired properties, including high strength and high formability under a variety of temper conditions, including Tx temper conditions (where Tx tempers can include T1, T4, T5, T6, T7, or T8 tempers), W temper, O temper, or F temper. In some examples, such as for 7xxx alloys, the resulting metal product has a yield strength of from approximately 400 MPa to 650 MPa (e.g., from 450 MPa to 625 MPa, from 475 MPa to 600 MPa, or from 500 MPa to 575 MPa). For example, the yield strength can be approximately 400 MPa, 410 MPa, 420 MPa, 430 MPa, 440 MPa, 450 MPa, 460 MPa, 470 MPa, 480 MPa, 490 MPa, 500 MPa, 510 MPa, 520 MPa, 530 MPa, 540 MPa, 550 MPa, 560 MPa, 570 MPa, 580 MPa, 590 MPa, 600 MPa, 610 MPa, 620 MPa, 630 MPa, 640 MPa, or 650 MPa. Optionally, the metal product having a yield strength of from approximately 400 MPa to 650 MPa can be in the T6 temper. In some examples, the resulting metal product has a maximum yield strength of from approximately 560 MPa to 650 MPa. For example, the maximum yield strength of the metal product can be approximately 560 MPa, 570 MPa, 580 MPa, 590 MPa, 600 MPa, 610 MPa, 620 MPa, 630 MPa, 640 MPa, or 650 MPa. Optionally, the metal product having a maximum yield strength of from approximately 560 MPa to 650 MPa can be in the T6 temper. Optionally, the metal product can have a yield strength of from approximately 500 MPa to approximately 650 MPa after paint baking the metal product in the T4 temper (i.e., without any artificial aging). For 5xxx alloys, such as in O-temper, the yield strength may be at least 100 MPA and in the H19 temper, the yield strength may be at least 300 MPa.

In some examples, the resulting metal product has an ultimate tensile strength of from approximately 500 MPa to 650 MPa (e.g., from 550 MPa to 625 MPa or from 575 MPa to 600 MPa). For example, the ultimate tensile strength can be approximately 500 MPa, 510 MPa, 520 MPa, 530 MPa, 540 MPa, 550 MPa, 560 MPa, 570 MPa, 580 MPa, 590 MPa, 600 MPa, 610 MPa, 620 MPa, 630 MPa, 640 MPa, or 650 MPa. Optionally, the metal product having an ultimate tensile strength of from approximately 500 MPa to 650 MPa is in the T6 temper.

In some examples, the resulting metal product has an interior bend angle of from approximately 1000 to 1600 (e.g., from approximately 1100 to 1550 or from approximately 1200 to 150°). For example, the bend angle of the resulting metal product can be approximately 100°, 101°, 102°, 103°, 104°, 105°, 106°, 107°, 108°, 109°, 110°, 111°, 112°, 113°, 114°, 115°, 116°, 117°, 118°, 119°, 120°, 121°, 122°, 123°, 124°, 125°, 126°, 127°, 128°, 129°, 130°, 131°, 132°, 133°, 134°, 135°, 136°, 137°, 138°, 139°, 140°, 141°, 142°, 143°, 144°, 145°, 146°, 147°, 148°, 149°, 150°, 151°, 152°, 153°, 154°, 155°, 156°, 157°, 158°, 159°, or 160°. Optionally, the metal product having a bend angle of from approximately 1000 to 1600 can be in the T6 temper.

Methods of Use

The alloys and methods described herein can be used in automotive and/or transportation applications, including motor vehicle, aircraft, and railway applications, or any other desired application. In some examples, the alloys and methods can be used to prepare motor vehicle body part products, such as bumpers, side beams, roof beams, cross beams, pillar reinforcements (e.g., A-pillars, B-pillars, and C-pillars), inner panels, outer panels, side panels, inner hoods, outer hoods, or trunk lid panels. The aluminum alloys and methods described herein can also be used in aircraft or railway vehicle applications, to prepare, for example, external and internal panels.

The alloys and methods described herein can also be used in electronics applications. For example, the alloys and methods described herein can also be used to prepare housings for electronic devices, including mobile phones and tablet computers. In some examples, the alloys can be used to prepare housings for the outer casing of mobile phones (e.g., smart phones) and tablet bottom chassis.

In some cases, the alloys and methods described herein can be used in industrial applications. For example, the alloys and methods described herein can be used to prepare products for the general distribution market.

EXAMPLES Example 1

Eight samples were prepared based on AA5182 with the composition shown below. Sample A was a control, with no Ca addition (8 ppm Ca was present in the alloy), while in Sample B, Ca was added. Similarly, Samples C and E were controls while Sample D had Ca added. Each sample had a gauge of 12.6 mm. Samples A-B were cast at a speed of 3 m/min and Samples C-E were cast at 4 m/min. Samples AA, BB, and CC were prepared as described above and were cast as 3 m/min. Sample AA had 36 ppm Ca, and Samples BB and CC were prepared by using the composition of Sample AA and then adding Ca to provide samples with 72 ppm Ca, and 199 ppm Ca, respectively. The Ca was added by adding a short piece of Ca containing rod at specified intervals until the desired Ca concentration was reached.

Sample Si Fe Cu Mn Mg Ti Ca (ppm) Comparative A 0.09 0.24 0.003 0.32 4.49 0.01 8 B 0.09 0.24 0.003 0.32 4.49 0.01 83 Comparative C 0.056 0.201 0.001 0.306 4.571 0.013 1 D 0.057 0.199 0.001 0.306 4.547 0.014 62 Comparative E 0.057 0.200 0.001 0.305 4.579 0.014 1 Comparative AA 0.08 0.22 0.02 0.36 4.3 0.014 36 BB 0.08 0.22 0.02 0.36 4.3 0.014 72 CC 0.08 0.22 0.02 0.36 4.3 0.014 199

Following casting, a 200 mm wide slab was then collected and photographed. A photograph of Sample A is shown in FIG. 1 and a photograph of Sample B is shown in FIG. 2 . As evident from visual inspection, Sample A had a shinier surface than Sample B, indicating a positive effect from Ca addition. Photographs of Samples C-E are shown in FIG. 3 . As shown in FIG. 3 , the exudates appeared smaller with Ca addition. FIG. 4 shows a zoomed in photograph of Samples C and D, with Sample C shown on the left and Sample D shown on the right. Sample D had more uniform porosity associated with the exudates and had smaller exudates. The intermetallic particles were small in both Samples C and D, though smaller in Sample D.

Intermetallic particle content, including Al_(m)FeMn, α-Al(FeMn)Si, Al₃Fe, and Mg₂Si (e.g., iron-based intermetallic particles (Fe-IMCs)), was evaluated with respect to Ca content in Samples AA, BB, and CC. FIG. 10 shows a number of pores 1010 which were formed due to a lack of proper degassing. FIG. 11 shows the presence of Fe-IMCs in the AA5182 aluminum alloy. Additionally, FIG. 12 is a cross-sectional composite view of the AA5182 aluminum alloy. FIG. 12 shows that the pores 1010 formed throughout the bulk of the AA5182 aluminum alloy, due to a lack of proper degassing.

Example 2

Four samples were prepared based on AA6XXX series aluminum alloys (e.g., X615) with the composition shown below. Samples F, H, I, J and L were controls, with no Ca addition (6-7 ppm Ca was present in the alloy), while in Samples G and K, Ca was added as described in Example 1 above. Each sample had a gauge of 12.6 mm. Samples F-I were cast at a speed of 3 m/min and Samples J-L were cast at a speed of 4 m/min. Sample F was produced having a hydrogen content of 0.16 ppm, Sample G was produced having a hydrogen content of 0.22 ppm, Sample H was produced having a hydrogen content of 0.19 ppm, and Sample I was produced having a hydrogen content of 0.30 ppm. Samples J-L were produced having the same hydrogen content.

Sample Si Fe Cu Mn Mg Ti Cr Ca (ppm) Comparative F 0.57 0.25 0.52 0.20 0.71 0.02 0.04 6 G 0.59 0.26 0.53 0.20 0.73 0.02 0.04 61 Comparative H 0.59 0.25 0.53 0.20 0.73 0.02 0.04 7 Comparative I 0.58 0.25 0.52 0.20 0.72 0.02 0.04 7 Comparative J 0.581 0.226 0.525 0.200 0.688 0.026 0.001 2 K 0.579 0.225 0.521 0.198 0.683 0.025 0.001 51 Comparative L 0.579 0.225 0.522 0.199 0.684 0.026 0.001 2 Comparative DD 0.52 0.22 0.52 0.19 0.67 0.02 0.03 36 EE 0.52 0.22 0.52 0.19 0.67 0.02 0.03 72

Again, each sample was photographed. A photograph of Sample F is shown in FIG. 5 , a photograph of Sample G is shown in FIG. 6 , a photograph of Sample H is shown in FIG. 7 , and a photograph of Sample I is shown in FIG. 8 . From a visual inspection, Sample I had the best surface appearance. With all else being the same, increased hydrogen content deteriorated the surface appearance. A photograph of Sample J is shown on the far left in FIG. 9 , a photograph of Sample K is shown in the middle of FIG. 9 , and a photograph of Sample L is shown on the far fight in FIG. 9 . As seen by visual inspection, Sample K, including Ca addition, had a superior surface appearance, indicating less surface defects.

Samples DD and EE were prepared as described above, including 36 ppm Ca and 72 ppm Ca, respectively. Intermetallic particle content, including dendritic α-Al(FeMn)Si, platelet β-AlFeSi, Q-Al₅Cu₂MgsSi₆ (e.g., Fe-IMCs), and Al₂Cu, was evaluated with respect to Ca content. The pores 1010 that formed as shown in FIG. 13 were due to a lack of proper degassing. FIG. 14 shows the presence of Fe-IMCs and Al₂Cu in the X615 aluminum alloy. Additionally, FIG. 15 is a cross-sectional composite view of the X615 aluminum alloy. FIG. 15 shows that the pores 1010 formed throughout the bulk of the X615 aluminum alloy, due to a lack of proper degassing. As shown in FIG. 15 , larger Fe-IMCs formed near the center of the bulk of the X615 aluminum alloy, which is attributed to centerline segregation occurring while producing the X615 aluminum alloy.

Example 3

Two samples were prepared based on an AA3104 aluminum alloy, with the composition shown below. In Samples GG, Ca was added as described in Example 1 above.

Sample Si Fe Cu Mn Mg Ti Ca (ppm) Comparative FF 0.21 0.45 0.18 0.95 1.04 0.01 29 GG 0.21 0.45 0.18 0.95 1.04 0.01 107

Samples FF and GG were prepared as described above, including 29 ppm Ca and then addition of Ca so that Sample GG had 107 ppm Ca. Intermetallic particle content, including α-Al(FeMn)Si, Al₆FeMn (e.g., Fe-IMCs), and Mg₂Si, was evaluated with respect to Ca content. Ca addition in Sample GG increased the amount of α-Al(FeMn)Si allowed to form and decreased the amount of Al₆FeMn allowed to form, as shown in FIG. 19 . In Samples FF and GG. the relative proportion of intermetallic phases in the extracted particles, quantified using XRD, is shown below.

Sample α-Al(FeMn)Si Al₆FeMn Mg₂Si Comparative FF 95.59 4.4 0.01 GG 99.88 0.1 0.02

As shown in the above table, adding Cato increase the Ca content resulted in an increased in the proportion of α-Al(FeMn)Si and a decrease in Al₆FeMn. Such a proportion of alpha may lead to decreased homogenization times during downstream processing and improved intermetallic distribution in the final product, thus improve the final sheet properties. Pores 1010 formed as shown in FIG. 16 due to a lack of proper degassing. FIG. 17 shows the presence of Fe-ImCs and Mg₂Si in the AA3104 aluminum alloy. Additionally, FIG. 18 is a cross-sectional composite view of the AA3104 aluminum alloy. FIG. 18 shows that the pores 1010 formed throughout the bulk of the AA3104 aluminum alloy due to a lack of proper degassing.

Reference has been made in detail to various examples of the disclosed subject matter, one or more examples of which were set forth above. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made in the present subject matter without departing from the scope or spirit of the disclosure. For instance, features illustrated or described as part of one embodiment may be used with another embodiment to yield a still further embodiment.

Illustrations of Suitable Methods and Alloy Products

Illustration 1 is a process for casting an aluminum alloy, comprising: melting an aluminum alloy to form a molten aluminum alloy, wherein the molten aluminum alloy comprises Mg; adding at least 30 ppm Ca to the molten aluminum alloy; and continuously casting the molten aluminum alloy to form a cast aluminum alloy.

Illustration 2 is the process of any preceding or subsequent illustration, wherein the aluminum alloy does not comprise Mg, and wherein the process further comprises adding Mg to the molten aluminum alloy.

Illustration 3 is the process of any preceding or subsequent illustration, wherein the aluminum alloy article is a 5xxx series aluminum alloy, a 6xxx series aluminum alloy, or a 7xxx series aluminum alloy.

Illustration 4 is the process of any preceding or subsequent illustration, wherein the Ca is added to the molten aluminum alloy in an amount from 50 ppm to 500 ppm.

Illustration 5 is the process of any preceding or subsequent illustration, wherein the Ca is added to the molten aluminum alloy in an amount from 50 ppm to 400 ppm.

Illustration 6 is the process of any preceding or subsequent illustration, wherein the Ca is added to the molten aluminum alloy in an amount from 50 ppm to 250 ppm.

Illustration 7 is the process of any preceding or subsequent illustration, wherein the Ca is added to the molten aluminum alloy in a trough of a continuous caster.

Illustration 8 is the process of any preceding or subsequent illustration, wherein the molten aluminum alloy is substantially free of Be.

Illustration 9 is the process of any preceding or subsequent illustration, wherein the cast aluminum alloy comprises at least 0.3% by weight Mg.

Illustration 10 is the process of any preceding or subsequent illustration, wherein the cast aluminum alloy comprises an oxide surface layer.

Illustration 11 is the process of any preceding or subsequent illustration, further comprising cooling the cast aluminum alloy upon exit from a continuous caster.

Illustration 12 is the process of any preceding or subsequent illustration, wherein the cooling step comprises water quenching the cast aluminum alloy.

Illustration 13 is the process of any preceding or subsequent illustration, wherein the cast aluminum alloy is coiled.

Illustration 14 is the process of any preceding or subsequent illustration, further comprising: solutionizing the aluminum alloy article; quenching the aluminum alloy article; and aging the aluminum alloy article.

Illustration 15 is the process of any preceding or subsequent illustration, wherein a cold rolling step is performed.

Illustration 16 is an aluminum alloy article prepared according to the process of any preceding or subsequent illustration.

Illustration 17 is the aluminum alloy of any preceding or subsequent illustration, wherein the aluminum alloy article is an aluminum alloy sheet, an aluminum alloy plate, or an aluminum alloy shate.

Illustration 18 is the aluminum alloy of any preceding or subsequent illustration, wherein the aluminum alloy article is an automotive body part, a motor vehicle part, a transportation body part, an aerospace body part, or an electronics housing.

Illustration 19 is the aluminum alloy of any preceding illustration, wherein the surface of the product has at least 10% less surface defects than a product formed without addition of calcium.

All patents, publications, and abstracts cited above are incorporated herein by reference in their entireties. Various embodiments of the invention have been described in fulfillment of the various objectives of the invention. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Numerous modifications and adaptions thereof will be readily apparent to those skilled in the art without departing from the spirit and scope of the present invention as defined in the following claims. 

1. A process for casting an aluminum alloy, comprising: melting an aluminum alloy to form a molten aluminum alloy, wherein the molten aluminum alloy comprises Mg; adding at least 30 ppm Ca to the molten aluminum alloy; and continuously casting the molten aluminum alloy to form a cast aluminum alloy.
 2. The process of claim 1, wherein the aluminum alloy does not comprise Mg, and wherein the process further comprises adding Mg to the molten aluminum alloy.
 3. The process of claim 1, wherein the aluminum alloy article is a 5xxx series aluminum alloy, a 6xxx series aluminum alloy, or a 7xxx series aluminum alloy.
 4. The process of claim 1, wherein the Ca is added to the molten aluminum alloy in an amount from 50 ppm to 500 ppm.
 5. The process of claim 1, wherein the Ca is added to the molten aluminum alloy in an amount from 50 ppm to 400 ppm.
 6. The process of claim 1, wherein the Ca is added to the molten aluminum alloy in an amount from 50 ppm to 250 ppm.
 7. The process of claim 1, wherein the Ca is added to the molten aluminum alloy in a trough of a continuous caster.
 8. The process of claim 1, wherein the molten aluminum alloy is substantially free of Be.
 9. The process of claim 1, wherein the cast aluminum alloy comprises at least 0.3% by weight Mg.
 10. The process of claim 1, wherein the cast aluminum alloy comprises an oxide surface layer.
 11. The process of claim 1, further comprising cooling the cast aluminum alloy upon exit from a continuous caster.
 12. The process of claim 11, wherein the cooling step comprises water quenching the cast aluminum alloy.
 13. The process of claim 1, wherein the cast aluminum alloy is coiled.
 14. The process of claim 1, further comprising: solutionizing the aluminum alloy article; quenching the aluminum alloy article; and aging the aluminum alloy article.
 15. The process of claim 1, wherein a cold rolling step is performed.
 16. An aluminum alloy article prepared according to the process of claim
 1. 17. The aluminum alloy article of claim 16, wherein the aluminum alloy article is an aluminum alloy sheet, an aluminum alloy plate, or an aluminum alloy shate.
 18. The aluminum alloy article of claim 16, wherein the aluminum alloy article is an automotive body part, a motor vehicle part, a transportation body part, an aerospace body part, or an electronics housing.
 19. The aluminum alloy article of claim 16, wherein the surface of the product has at least 10% less surface defects than a product formed without addition of calcium. 